The present invention is directed to azabenzimidazoles of formula I, which as inhibitors of platelet activating factor (PAF) and of LTD.sub.4 receptor binding sites are useful in the treatment or prevention to of asthma, arthritis, psoriasis and a wide range of inflammatory disorders.
Kreft et al., in U.S. Pat. No. 4,661,596, describe compounds which are disubstituted naphthalenes, dihydronaphthalenes or tetralins having the formula ##STR1## wherein the dotted lines represent optional double bonds, R.sup.a is 2-pyridvl, 2-quinolyl, 2-pyrazinyl, 2-quinoxalinyl, 2-thiazolyl, 2-benzothiazolyl, 2-oxazolyl, 2-benzoxazolyl, 1-alkyl-2-imidazolyl or 1-alkyl-2-benzimidazolyl and R.sup.b is hydroxy, lower alkoxy, lower alkyl or perfluoro alkyl. These compounds inhibit lipoxygenase enzyme and antagonize the effects of leukotriene D4, and so are useful in the prevention and treatment of asthma.
Eggler et al., in copending International application PCT/US87/02745, filed Oct. 19, 1987 have described similarly active compounds, including chromans of the formula ##STR2## wherein R.sup.x is substantially defined as above, R.sup.z is aryl or heteroaryl, X.sup.a is, for example, oxygen or CH.sub.2, and X.sup.b is C.dbd.O or CHOH.
More recently, International Application PCT/US89/00975, Publication No. WO 89/08653, describes the preparation of 1-carbamylbenzvlimidazo[4,5-c]pyridines useful as PAF antagonists.